Jorge Ortiz, Chris R. Baker, Daekyeong Moon, Rodrigo Fonseca, and Ion Stoica. Beacon Location Service: A Location Service for Point-to-Point Routing in Wireless Sensor Networks.  International Conference in Information Processing in Sensor Networks: Special Track on Platform Tools and Design Methods For Network Embedded Sensors 2007 (IPSN '07).  [pdf][ppt] [code]

Related Work: Small State and Small Stretch Routing Protocol for Large Wireless Sensor Networks [pdf]